Sacrifical anode construction

ABSTRACT

A sacrificial anode construction in which the anode is supported in a loose-fitting porous container within the vessel to be protected. The container is constructed to substantially cease liquid flow around the anode when desired so that the anode can be replaced without the loss of an appreciable amount of liquid within the vessel.

United States Patent William D. Mackintosh Tulsa, Okla.

Mar. 17, 1969 Oct. 26, 1971 Atlantic Richfield Company New York, NY.

Inventor Appl. N 0. Filed Patented Assignee SACRIFICAL ANODECONSTRUCTION 11 Claims, 7 Drawing Figs.

References Cited UNITED STATES PATENTS 8/1888 Siebel 393,072 11/1988Marquand 204/196 1,335,210 3/1920 Von Wurstemberger 204/196 2,244,3226/1941 Zoller et a1. 204/197 2,666,026 1/1954 Gibbs 204/197 2,816,06912/1957 Andrus 204/196 3,012,958 12/1961 Vixler 204/197 3,074,865 1/1963Gaysowski... 204/196 3,138,549 6/1964 Adair 204/197 3,515,654 6/1970Bordalen et a1 204/147 Primary ExaminerT. Tung Attorney-McLean, Mortonand Boustead ABSTRACT: A sacrificial anode construction in which theanode is supported in a loose-fitting porous container within the vesselto be protected. The container is constructed to substantially ceaseliquid flow around the anode when desired so that the anode can bereplaced without the loss of an appreciable amount of liquid within thevessel.

PAIENTEDnm 26 mm 3. 6 1 6,421

sum 1 OF 3 INVI-IN'IOR WILLIAM D. MACKINTOSH HYVWGM I,

PATENTEDUET 26 1971 SHEET 3 OF 3 INVl-ZN'IOR WILLIAM D. MACKINTOSHSACRIFICAL ANODE CONSTRUCTION SACRIFICIAL ANODE CONSTRUCTION Thisinvention relates to a novel sacrificial anode construction useful inliquid-containing vessels below the liquid level line. In particular,this invention relates to a sacrificial anode construction in which theanode is contained within a loosefitting fluid permeable containerwherein the liquid can permeate the container and contact the anodewhile in use but which allows replacement of the anode without anappreciable loss of liquid and without having to shutdown and drain thevessel.

The use of sacrificial anodes made of suitable metals, usually aluminumor magnesium or their alloys, in liquid-containing vessels is wellknown. By providing such an anode below the liquid level, corrosion ofthe container vessel is diminished and, instead, the anode is corroded.Many variations for the installation of sacrificial anodes are known. Insome cases, bundles of anodes are held in strings and suspended in theliquid. In many vessels the sacrificial anode is made an integral partof the vessel wall during construction. Once this anode has beensubstantially corroded away, however, the vessel has to be drained and anew anode placed inside of the vessel. This procedure is not onlyinconvenient and expensive, with a substantial loss in production due tothe downtime, but often the anodes are not changed until long after theyare expended with consequent corrosion and ultimate loss of the vessel.

It is an object of this invention to provide a sacrificial anodeconstruction particularly useful in liquid-containing vessels whichprovides for easy replacement of the anode while the vessel is fullwithout an appreciable loss of fiuid from the vessel. It is anotherobject of this invention to protect the anode in the vessel from erosionwhich greatly shortens the life of the anode. It is another object ofthis invention to provide an anode head which does not provideinsulation for the anode through the tank shell, the insulation beingprovided on the anode. This simplified construction of the anode headmakes it possible for the head to be reused on new anodes.

These and other objects are attained by enclosing the anode in a loosefitting container secured to the vessel wall. The permeability of thecontainer can vary from slightly porous to very porous but in each case,the container provides a means to substantially cease liquid flow duringchanging of the anode. The containers are substantially permanentlyenclosed in the vessel wall and the anodes are insertable from theexterior of the vessel allowing easy replacement. The anodes can, ifdesired, be placed in a nylon bag to protect them from erosion.

The invention will be discussed in more detail with reference to theappended drawings in which:

FIG. I is an enlarged view of the mount for the sacrificial anode;

FIG. 2 is a cross-sectional view of one embodiment of this invention inwhich the container is a rigid porous member;

FIGS. 3 and 4 are cross-sectional views of a second embodiment of thisinvention in which the container includes a slidable sleeve;

FIGS. 5 and 6 are cross-sectional views of a third embodiment of thisinvention in which the container has an openable end; and

FIG. 7 shows a modification of the embodiment of FIGS. 3 and 4.

Referring now to FIG. 1, sacrificial anode 10 is shown supported innipple 14 which is mounted on tank shell 12, only a portion of which isshown, to provide an opening extending through shell 12. The anode issupported by threaded rod 16 running through the center of the anode.Rod 16 is secured to anode head by a mated, threaded rod 18, as shown,or, if desired, rods 16 and 18 can be a single element. The rods 16, 18electrically connect anode 10 to the exterior of tank shell 12 andthrough wire 17 to the shell at a point remote from nipple 14. Rods l6,l8 are insulated from anode head 20 by plastic sleeve 22 and plasticwashers 24, 26. Steel washers 28, 30 can be used to provide support atthe connection if desired. Victaulic cap 32 connects anode head 20 tothe nipple 14. Additional insulating material 34 is placed between anodel0 and nipple 14 to ensure that no contact occurs. Insulating material34 can also be used to provide additional support for anode l0 and toassist in sealing nipple 14 so that the liquid within tank 12 does notleak out.

FIG. 2 illustrates one embodiment of this invention which is in the formof a cylindrical member 40 constructed of a suitable porous ceramicmaterial. such as alumina, which allows passage of the liquid containedwithin tank I2 around anode 10 in a sufficient amount to protect thetank against corrosion but in an amount insufficient to allowsubstantial leakage during replacement of anode 10.

FIG. 3 shows another embodiment of the invention. In this form of theinvention the anode is supported within a container formed by twoimpervious sleeves 50 and 52, preferably made of a metal such asstainless steel coated to provide a liquid seal, e.g. PVC-coated, orneoprene-coated nylon, which contain a number of holes 54 and 54' in-thesides 50 and 52, respectively. The ends of sleeves 50 and-52 within thevessel are solid and sleeve 52 is rigidly attached to the vessel wall 12while sleeve 50 is slidable along its axis. Slidable sleeve 50 can bemoved from the exterior of the vessel by rods 56 attached to the sleeveat 58 and running through seals 60 in the vessel wall 12. Anode 10 isattached to anode head 20 in the same manner as noted above, i.e., by arod and sealed. Insulation 34 is provided to insulate the nipple andvessel wall from the anode. To protect anode 10 from erosion, so that itis not prematurely made ineffective, the anode can, when desired, beenclosed in a protective bag 35 made of a material such as nylon. Inuse, sleeves 50 and 52 are arranged in tank 12 with the holes 54, 54'concentric as shown in FIG. 4. Thus, liquid can easily enter intocontact with the mode. When the anode is to be removed, and changed asin the manner discussed above, sleeve 50 is moved along its axis alength equal to or slightly greater than the diameter of holes 54 bymeans of rods 56 such that holes 54 in the inner sleeve 52 are closed bythe solid spaced between holes 54 in the outer sleeve 50 and vice versaas indicated generally in FIG. 3. This stops the flow of liquid into thecontainer formed by the sleeves and limits the loss of fluid on changingof anode 10 to that amount which is trapped in the container. Cylinder50 is moved back to its original operation position so that the holesare again concentric after a new anode I0 is in place. In themodification of FIG. 7 the inner and outer sleeves 50' and 52' areconstructed with holes 54" and 54", respectively, in the sides 50 and52' much as sleeves 50 and 52. However, the holes 54" and 54" registerto permit liquid to flow around anode 10 by a rotary movement of sleeves50' and 52' rather than a reciprocating movement as in the embodiment ofFIG. 3. This rotary movement is accomplished by turning the anode head20 which is rigidly attached to anode 10 through rod I6 and pins 17, orother suitable means, and dished plate 15. Snap rings 19 hold plate 15on rod 16 and removable pins 13 secure plate I5 to sleeve 52 to completethe connection. In this embodiment, rod 16 is sealed at anode head 20.The end of rod 16 at plate 15 is square to translate rotary movement ofhead 20 to plate 15 and pins 13 secure plate 15 to sleeve 52. Toelectrically insulate anode 10, plate 15 should be made of a suitablenonconductive material.

FIGS. 5 and 6 show another embodiment of this invention. In thisembodiment, the container within which anode 10 is supported consists ofan open-ended rigid, impervious sleeve 62. Rods 64, 66 which extend fromthe exterior of the vessel through wall 12 into the liquid have attachedat the inner end a cap 68 of solid, impervious material. Rods 64, 66pass through vessel wall 12 through seals 70. Anode 10 is againconnected to anode head 20 by suitable means such as shown in FIG. I. Inuse, cap 68 is maintained at a position such that it is away from theopen end of sleeve 62, as shown in FIG. 6. In such a position, theliquid in the vessel is free to contact the anode 10 by entry throughthe open end of sleeve 62. To change the anode, cap 68 is moved back toa position in contact with the sleeve 62 as shown in FIG. 5 to sealsleeve 62. This operation is accomplished by pulling rods 64, 66,slidably sealed in the vessel wall 12. Anode is changed as before andthe only loss of liquid is that liquid which is trapped inside thecontainer or sleeve 62. As noted before, this trapped liquid is arelatively insignificant part of the total liquid in the vessel.

It has thus been shown that this novel construction allows the easyreplacement of sacrificial anodes from the exterior of the vessel andwithout appreciable loss of fluid.

lclaim:

l. A cathodic protection assembly comprising a vessel adapted to containa liquid, a sacrificial anode construction extending through an openingin the wall thereof at a point other than the top of said vessel so thatremoval of the anode can cause substantial loss of liquid, aliquid-permeable container in said vessel, said container having anopening in communication with the exterior of said vessel, saidcontainer preventing a substantial loss of liquid through said openingwhen said anode is removed, at least one anode within said container,said anode being removable from outside said vessel, said containerbeing such that it is not removable through said opening in said vesselwall, and means for liquid sealing said anode and container from theexterior of the said vessel.

2. The anode construction of claim I wherein said permeable container isa rigid, porous ceramic body loosely fitting about said anode.

3. The anode construction of claim 2 wherein said ceramic is alumina.

4. The anode construction of claim 2 wherein the porosity of thecontainer is such that it prevents a substantial loss of liquid throughsaid container when said anode .is replaced.

5. The anode construction of claim 1 wherein said permeable container isa solid body containing at least one normally open orifice and meansoperable from outside laid vessel for opening and closing said at leastone orifice.

6. The anode construction of claim 5 wherein said container comprises apair of concentric sleeves each having at least one orifice in its wall,the orifices in said pair of sleeves normally being in line with oneanother to allow the flow of liquid therethrough to contact said anode,at least one ot'said sleeves being movable relative to the other of saidsleeves, and means for moving one of said sleeves so that the orificesare no longer in line so that liquid flow through the orifices to saidanode is substantially stopped.

7. The anode construction of claim 6 wherein the outer sleeve ismovable, and means for moving said outer sleeve comprising rodsconnected to said outer sleeve and extending through said vessel wall tothe exterior of said vessel.

8. The anode construction of claim 6 wherein the inner sleeve is movableand means for moving said inner sleeve so that the orifices are nolonger in line and liquid flow through said orifices is substantiallystopped.

9. The anode construction of claim 8 wherein said means for moving saidinner sleeve comprises rotatable means extending from the exterior ofsaid vessel through said vessel wall, said rotatable means beingconnected to said inner sleeve so that rotation of said rotatable meansrotates said inner sleeve.

10. The anode construction of claim 5 wherein said containcr comprisesan open-ended rigid sleeve, and means for closing said open end.

11. The anode construction of claim 10 wherein said means for closingsaid open end is at least one rod extending from outside of and throughsaid vessel wall, said at least one rod carrying a cap means in theinterior of said vessel. said cap means being positioned adjacent saidopen end to close and open said open end upon movement of said redmeans.

# i l Q

2. The anode construction of claim l wherein said permeable container isa rigid, porous ceramic body loosely fitting about said anode.
 3. Theanode construction of claim 2 wherein said ceramic is alumina.
 4. Theanode construction of claim 2 wherein the porosity of the container issuch that it prevents a substantial loss of liquid through saidcontainer when said anode is replaced.
 5. The anode construction ofclaim 1 wherein said permeable container is a solid body containing atleast one normally open orifice and means operable from outside saidvessel for opening and closing said at least one orifice.
 6. The anodeconstruction of claim 5 wherein said container comprises a pair ofconcentric sleeves each having at least one orifice in its wall, theorifices in said pair of sleeves normally being in line with one anotherto allow the flow of liquid therethrough to contact said anode, at leastone of said sleeves being movable relatiVe to the other of said sleeves,and means for moving one of said sleeves so that the orifices are nolonger in line so that liquid flow through the orifices to said anode issubstantially stopped.
 7. The anode construction of claim 6 wherein theouter sleeve is movable, and means for moving said outer sleevecomprising rods connected to said outer sleeve and extending throughsaid vessel wall to the exterior of said vessel.
 8. The anodeconstruction of claim 6 wherein the inner sleeve is movable and meansfor moving said inner sleeve so that the orifices are no longer in lineand liquid flow through said orifices is substantially stopped.
 9. Theanode construction of claim 8 wherein said means for moving said innersleeve comprises rotatable means extending from the exterior of saidvessel through said vessel wall, said rotatable means being connected tosaid inner sleeve so that rotation of said rotatable means rotates saidinner sleeve.
 10. The anode construction of claim 5 wherein saidcontainer comprises an open-ended rigid sleeve, and means for closingsaid open end.
 11. The anode construction of claim 10 wherein said meansfor closing said open end is at least one rod extending from outside ofand through said vessel wall, said at least one rod carrying a cap meansin the interior of said vessel, said cap means being positioned adjacentsaid open end to close and open said open end upon movement of said rodmeans.